    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *     http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.configuration2.tree;
    018
    019import java.util.List;
    020import java.util.Map;
    021
    022/**
    023 * <p>
    024 * Definition of an interface which allows resolving a (property) key for
    025 * different manipulating operations.
    026 * </p>
    027 * <p>
    028 * This interface is used when interacting with a node model. It is an
    029 * abstraction over a concrete {@link ExpressionEngine} instance. It also
    030 * implements some functionality for creating special helper objects for the
    031 * processing of complex update operations.
    032 * </p>
    033 *
    034 * @version $Id: NodeKeyResolver.java 1624601 2014-09-12 18:04:36Z oheger $
    035 * @since 2.0
    036 * @param <T> the type of the nodes supported by this resolver
    037 */
    038public interface NodeKeyResolver<T>
    039{
    040    /**
    041     * Performs a query for the specified key on the given root node. This is a
    042     * thin wrapper over the {@code query()} method of an
    043     * {@link ExpressionEngine}.
    044     *
    045     * @param root the root node
    046     * @param key the key to be resolved
    047     * @param handler the {@code NodeHandler}
    048     * @return a list with query results
    049     */
    050    List<QueryResult<T>> resolveKey(T root, String key, NodeHandler<T> handler);
    051
    052    /**
    053     * Performs a query for the specified key on the given root node returning
    054     * only node results. Some operations require results of type node and do
    055     * not support attributes (e.g. for tracking nodes). This operation can be
    056     * used in such cases. It works like {@code resolveKey()}, but filters only
    057     * for results of type node.
    058     *
    059     * @param root the root node
    060     * @param key the key to be resolved
    061     * @param handler the {@code NodeHandler}
    062     * @return a list with the resolved nodes
    063     */
    064    List<T> resolveNodeKey(T root, String key, NodeHandler<T> handler);
    065
    066    /**
    067     * Resolves a key of an add operation. Result is a {@code NodeAddData}
    068     * object containing all information for actually performing the add
    069     * operation at the specified key.
    070     *
    071     * @param root the root node
    072     * @param key the key to be resolved
    073     * @param handler the {@code NodeHandler}
    074     * @return a {@code NodeAddData} object to be used for the add operation
    075     */
    076    NodeAddData<T> resolveAddKey(T root, String key, NodeHandler<T> handler);
    077
    078    /**
    079     * Resolves a key for an update operation. Result is a
    080     * {@code NodeUpdateData} object containing all information for actually
    081     * performing the update operation at the specified key using the provided
    082     * new value object.
    083     *
    084     * @param root the root node
    085     * @param key the key to be resolved
    086     * @param newValue the new value for the key to be updated; this can be a
    087     *        single value or a container for multiple values
    088     * @param handler the {@code NodeHandler}
    089     * @return a {@code NodeUpdateData} object to be used for this update
    090     *         operation
    091     */
    092    NodeUpdateData<T> resolveUpdateKey(T root, String key, Object newValue,
    093            NodeHandler<T> handler);
    094
    095    /**
    096     * Generates a unique key for the specified node. This method is used if
    097     * keys have to be generated for nodes received as query results. An
    098     * implementation must generate a canonical key which is compatible with the
    099     * current expression engine. The passed in map can be used by an
    100     * implementation as cache. It is created initially by the caller and then
    101     * passed in subsequent calls. An implementation may use this to avoid that
    102     * keys for nodes already encountered have to be generated again.
    103     *
    104     * @param node the node in question
    105     * @param cache a map serving as cache
    106     * @param handler the {@code NodeHandler}
    107     * @return a key for the specified node
    108     */
    109    String nodeKey(T node, Map<T, String> cache, NodeHandler<T> handler);
    110}